The present invention relates to a data driving circuit for an organic light emitting diode display, and more particularly, to a data driving circuit with a single D/A converter.
Digital data drivers for conventional organic light emitting displays normally use a storage register (digital latch), as a line buffer to store digital video signal in a signal cycle.
FIGS. 1A and 1B show a conventional 6-bit digital data driving scheme 10, in which binary bits of digital video data are loaded sequentially during a horizontal scan cycle. First, through data lines R[5]˜B[0], binary bits of digital video data are written to corresponding first latches 11, all controlled by a sampling signal applied by a shift register SRn. Next, through data lines R[5]˜B[0], subsequent digital video data of binary bits are written to corresponding first latches 21, all controlled by a sampling signal applied by a shift register SRn+1. Similarly, all the digital video data for a horizontal scan cycle is respectively stored into first latches. When the line buffer signal “LB” is asserted, all bits of digital video data stored in first latches 11 and 21 are written to the second latches 12, 22 and transmitted to the digital-to-analog converters DAC-Rn, DAC-Gn, DAC-Bn at the same time.
Data bit number increases with resolution, and the number of area-consuming storage registers and the number of digital-to-analog converters also increase. In the conventional layout of a digital driving circuit, when a data bit number increases with resolution, the number of storage registers and the number of the digital-to-analog converters also increase, and make layout more difficult due to limited horizontal layout area.